JP7158249B2 - SUBSTRATE PROCESSING METHOD, SUBSTRATE PROCESSING APPARATUS, AND STORAGE MEDIUM - Google Patents

Description

The disclosed embodiments relate to a substrate processing method, a substrate processing apparatus, and a storage medium.

Conventionally, in a substrate processing apparatus, the substrate is immersed in a phosphating solution to selectively etch the silicon nitride film out of the silicon nitride film (SiN) and the silicon oxide film (SiO ₂ ) laminated on the substrate. It is known to perform an etching process to remove the film (see Patent Literature 1).

JP 2013-232593 A

The present disclosure provides a technique capable of accurately etching a silicon nitride film even on a substrate in which silicon nitride films and silicon oxide films are highly laminated.

A substrate processing method according to one aspect of the present disclosure includes an etching step of etching a substrate having a silicon oxide film and a silicon nitride film formed thereon with a phosphating solution. In the etching step, the silicon concentration in the phosphating solution is set to a first silicon concentration at which the silicon oxide film is etched during a first time interval from the start time.

According to the present disclosure, it is possible to accurately etch the silicon nitride film even on a substrate in which silicon nitride films and silicon oxide films are highly laminated.

FIG. 1 is a schematic plan view of a substrate processing apparatus according to an embodiment. FIG. 2 is a schematic block diagram showing the configuration of an etching treatment bath according to the embodiment. FIG. 3A is a schematic diagram showing a cross-section of a substrate before etching. FIG. 3B is a schematic diagram showing the state of the substrate after the etching process has progressed. FIG. 3C is a schematic diagram showing the state of the substrate after the etching process has progressed further. FIG. 3D is a schematic diagram showing the state of the substrate after the etching process is finished. FIG. 4 is a diagram showing the transition of the silicon concentration in the etchant and the temperature of the etchant in the etching process according to the embodiment. FIG. 5 is a diagram showing an example of the relationship between the silicon concentration in the etchant and the etching rate in etching the silicon oxide film and the silicon oxide. FIG. 6 is a diagram showing an example of transition of the film thickness of the silicon oxide film when the silicon concentration in the etchant is the second concentration. FIG. 7 is a diagram for explaining etching processing in the substrate processing apparatus according to the embodiment; FIG. 8 is a diagram showing transitions of the silicon concentration in the etchant and the temperature of the etchant in the etching process according to Modification 1 of the embodiment. FIG. 9 is a diagram showing transitions of the silicon concentration in the etchant and the temperature of the etchant in the etching process according to Modification 2 of the embodiment. FIG. 10 is a diagram showing the transition of the silicon concentration in the etchant and the temperature of the etchant in the etching process according to Modification 3 of the embodiment. FIG. 11 is a diagram showing transitions of the silicon concentration in the etchant and the temperature of the etchant in the etching process according to Modification 4 of the embodiment. FIG. 12 is a diagram for explaining etching processing in the substrate processing apparatus according to Modification 5 of the embodiment. FIG. 13 is a diagram for explaining etching processing in the substrate processing apparatus according to Modification 6 of the embodiment. FIG. 14 is a diagram for explaining etching processing in a substrate processing apparatus according to Modification 7 of the embodiment. FIG. 15 is a flow chart showing the procedure of the etching process according to the embodiment.

Embodiments of a substrate processing method, a substrate processing apparatus, and a storage medium disclosed in the present application will be described in detail below with reference to the accompanying drawings. It should be noted that the present disclosure is not limited by the embodiments shown below. Also, it should be noted that the drawings are schematic, and the relationship of dimensions of each element, the ratio of each element, and the like may differ from reality. Furthermore, even between the drawings, there are cases where portions having different dimensional relationships and ratios are included.

Conventionally, in a substrate processing apparatus, the substrate is immersed in a phosphating solution to selectively etch the silicon nitride film out of the silicon nitride film (SiN) and the silicon oxide film (SiO ₂ ) laminated on the substrate. It is known to perform an etching process to

However, when selectively etching a silicon nitride film on a substrate in which many silicon nitride films and silicon oxide films are laminated (hereinafter also referred to as "highly laminated"), the components of the etched silicon nitride film are The route to discharge to the outside of the board becomes long. As a result, the concentration of silicon in the phosphating solution that enters the gaps formed between the silicon oxide films increases, and silicon oxide may precipitate on the silicon oxide films.

Therefore, it is expected that the silicon nitride film can be etched with high precision even on a substrate on which silicon nitride films and silicon oxide films are highly laminated.

<Configuration of substrate processing apparatus>
First, the configuration of a substrate processing apparatus 1 according to an embodiment will be described with reference to FIG. FIG. 1 is a schematic plan view of a substrate processing apparatus 1. FIG. In the following, to clarify the positional relationship, the X-axis, Y-axis and Z-axis are defined to be orthogonal to each other, and the positive direction of the Z-axis is defined as the vertically upward direction.

As shown in FIG. 1, the substrate processing apparatus 1 according to the embodiment includes a carrier loading/unloading section 2, a lot forming section 3, a lot placement section 4, a lot transport section 5, a lot processing section 6, a control 100.

The carrier loading/unloading unit 2 loads and unloads a carrier 9 containing a plurality of (for example, 25) substrates (silicon wafers) 8 arranged vertically in a horizontal posture.

The carrier loading/unloading unit 2 includes a carrier stage 10 on which a plurality of carriers 9 are placed, a carrier transport mechanism 11 for transporting the carriers 9, carrier stocks 12 and 13 for temporarily storing the carriers 9, a carrier 9 is provided.

The carrier loading/unloading section 2 transports the carrier 9 loaded onto the carrier stage 10 from the outside to the carrier stock 12 or the carrier mounting table 14 using the carrier transport mechanism 11 . That is, the carrier loading/unloading section 2 transports the carrier 9 accommodating a plurality of substrates 8 before being processed by the lot processing section 6 to the carrier stock 12 or the carrier table 14 .

The carrier stock 12 temporarily stores a carrier 9 containing a plurality of substrates 8 before being processed by the lot processing section 6 .

A plurality of substrates 8 are unloaded by a substrate transport mechanism 15, which will be described later, from the carrier 9 that is transported to the carrier table 14 and accommodates the plurality of substrates 8 before being processed in the lot processing section 6. FIG. A plurality of substrates 8 after being processed in the lot processing section 6 are carried from the substrate transport mechanism 15 to the carrier 9 which is placed on the carrier table 14 and does not contain the substrates 8 .

The carrier loading/unloading unit 2 uses a carrier transport mechanism 11 to transfer a carrier 9 that is placed on a carrier table 14 and accommodates a plurality of substrates 8 after being processed by the lot processing unit 6 to a carrier stock 13 or a carrier. Transport to stage 10 .

The carrier stock 13 temporarily stores a plurality of substrates 8 that have been processed by the lot processing unit 6 . The carrier 9 transported to the carrier stage 10 is carried out to the outside.

The lot forming section 3 is provided with a substrate transport mechanism 15 that transports a plurality of (for example, 25) substrates 8 . The lot forming section 3 transports a plurality of (for example, 25) substrates 8 by the substrate transport mechanism 15 twice to form a lot consisting of a plurality of (for example, 50) substrates 8 .

The lot formation unit 3 uses the substrate transport mechanism 15 to transport a plurality of substrates 8 from the carrier 9 mounted on the carrier mounting table 14 to the lot mounting unit 4, and mount the plurality of substrates 8 on the lot. A lot is formed by placing it on the part 4 .

A plurality of substrates 8 forming a lot are processed simultaneously by the lot processing section 6 . When forming a lot, the lots may be formed so that the surfaces of the substrates 8 on which the patterns are formed face each other. The lot may be formed so that all the faces facing one side.

The lot formation unit 3 also uses the substrate transport mechanism 15 to transport a plurality of substrates 8 from the lot processed by the lot processing unit 6 and placed on the lot placement unit 4 to the carrier 9 .

The substrate transport mechanism 15 includes, as a substrate supporting portion for supporting a plurality of substrates 8, an unprocessed substrate supporting portion (not shown) for supporting a plurality of substrates 8 before processing and a substrate supporting portion (not shown) for supporting a plurality of substrates 8 after processing. 8, there are two types of post-processing substrate supports (not shown). As a result, it is possible to prevent particles and the like adhering to the plurality of substrates 8 and the like before processing from being transferred to the plurality of substrates 8 and the like after processing.

The substrate transfer mechanism 15 changes the orientation of the plurality of substrates 8 from the horizontal orientation to the vertical orientation and from the vertical orientation to the horizontal orientation while the plurality of substrates 8 are being transferred.

The lot placing unit 4 temporarily places (stands by) the lot transported between the lot forming unit 3 and the lot processing unit 6 by the lot transporting unit 5 on the lot placing table 16 . The lot placement unit 4 is provided with a loading-side lot placement table 17 and an unloading-side lot placement table 18 .

A lot before processing is placed on the load-in side lot placing table 17 . A processed lot is placed on the carrying-out side lot placing table 18 . A plurality of substrates 8 for one lot are placed in a vertical posture on the loading-side lot placing table 17 and the unloading-side lot placing table 18 so as to be arranged side by side.

The lot transport unit 5 transports lots between the lot placement unit 4 and the lot processing unit 6 or between the insides of the lot processing unit 6 . The lot transport unit 5 is provided with a lot transport mechanism 19 for transporting lots.

The lot transport mechanism 19 has a rail 20 arranged along the lot placing section 4 and the lot processing section 6, and a moving body 21 that moves along the rail 20 while holding the lot. The moving body 21 is provided with a substrate holder 22 that holds a lot formed of a plurality of substrates 8 arranged vertically in the front-rear direction. The lot transport mechanism 19 constitutes a transport section.

The lot transporting unit 5 receives the lot placed on the load-in side lot placing table 17 by the substrate holder 22 of the lot transporting mechanism 19 and transfers the received lot to the lot processing unit 6 . The lot transporter 5 also receives the lot processed by the lot processing unit 6 with the substrate holder 22 of the lot transport mechanism 19 and delivers the received lot to the carry-out side lot table 18 . Furthermore, the lot transport unit 5 uses the lot transport mechanism 19 to transport the lot inside the lot processing unit 6 .

The lot processing unit 6 performs processing such as etching, cleaning, and drying on a lot formed of a plurality of substrates 8 arranged in a vertical posture. In the lot processing section 6, two etching processing devices 23, a cleaning processing device 24, a substrate holder cleaning processing device 25, and a drying processing device 26 are arranged side by side.

The etching processing device 23 performs etching processing on the lot. The cleaning processing device 24 performs cleaning processing of the lot. The substrate holder cleaning apparatus 25 performs cleaning processing of the substrate holder 22 . The drying processing device 26 performs a lot drying processing. In addition, the number of the etching processing apparatuses 23 is not limited to two, and may be one or three or more.

The etching processing apparatus 23 has a processing bath 27 for etching, a processing bath 28 for rinsing, and substrate elevating mechanisms 29 and 30 . Although not shown in FIG. 1, the etching processing apparatus 23 of the embodiment includes a plurality of processing tanks 27 for etching.

The processing tank 27 for etching stores a processing liquid for etching (hereinafter referred to as "etching liquid"). A processing liquid for rinsing (pure water or the like) is stored in the processing tank 28 for rinsing. Details of the processing bath 27 for etching will be described later. A plurality of substrates 8 forming a lot are vertically arranged and held in the front-to-rear direction by the substrate lifting mechanisms 29 and 30 .

The etching processing apparatus 23 receives the lot from the substrate holder 22 of the lot transport mechanism 19 by the substrate lifting mechanism 29, lowers the received lot by the substrate lifting mechanism 29, and immerses the lot in the etching solution in the processing tank 27. Etching is performed. The etching process is performed, for example, for about 1 to 3 hours.

Further, in the embodiment, by transporting a lot from one etching treatment tank 27 of the etching treatment apparatus 23 to another etching treatment tank 27, it is possible to continuously perform etching treatment under different conditions. can.

Thereafter, the etching processing apparatus 23 lifts the substrate lifting mechanism 29 to take out the lot from the processing bath 27 and transfer the lot from the substrate lifting mechanism 29 to the substrate holder 22 of the lot transport mechanism 19 .

Then, the lot is received by the substrate lifting mechanism 30 from the substrate holder 22 of the lot transport mechanism 19, and the received lot is lowered by the substrate lifting mechanism 30 so that the lot is immersed in the treatment liquid for rinsing in the treatment tank 28 and rinsed. process.

After that, the etching processing apparatus 23 lifts the substrate lifting mechanism 30 to take out the lot from the processing bath 28 and transfer the lot from the substrate lifting mechanism 30 to the substrate holder 22 of the lot transfer mechanism 19 .

The cleaning processing apparatus 24 has a processing tank 31 for cleaning, a processing tank 32 for rinsing, and substrate elevating mechanisms 33 and 34 . The cleaning treatment tank 31 stores a cleaning treatment liquid (SC-1 (a mixture of ammonia, hydrogen peroxide, and water), etc.). A processing liquid for rinsing (pure water or the like) is stored in the processing tank 32 for rinsing. A plurality of substrates 8 for one lot are arranged vertically in the front-to-rear direction and held by the substrate lifting mechanisms 33 and 34 .

The drying processing apparatus 26 has a processing tank 35 and a substrate elevating mechanism 36 that moves up and down with respect to the processing tank 35 . A drying processing gas (IPA (isopropyl alcohol), etc.) is supplied to the processing bath 35 . The substrate lifting mechanism 36 holds a plurality of substrates 8 for one lot side by side in a vertical posture.

The drying processing apparatus 26 receives the lot from the substrate holder 22 of the lot transport mechanism 19 by the substrate lifting mechanism 36, lowers the received lot by the substrate lifting mechanism 36, carries it into the processing bath 35, and supplies it to the processing bath 35. The lot is dried using a drying process gas. Then, the drying processing device 26 lifts the lot by the substrate lifting mechanism 36 and transfers the dried lot from the substrate lifting mechanism 36 to the substrate holder 22 of the lot transfer mechanism 19 .

The substrate holder cleaning processing apparatus 25 has a processing bath 37, and can supply a processing liquid for cleaning and a drying gas to the processing bath 37. After the treatment liquid is supplied, the substrate holder 22 is cleaned by supplying dry gas.

The control unit 100 controls the operation of each unit of the substrate processing apparatus 1 (carrier loading/unloading unit 2, lot formation unit 3, lot placement unit 4, lot transport unit 5, lot processing unit 6). The control section 100 controls the operation of each section of the substrate processing apparatus 1 based on signals from switches or the like.

The control unit 100 is composed of a computer, for example, and has a computer-readable storage medium 38 . The storage medium 38 stores programs for controlling various processes executed in the substrate processing apparatus 1 .

The control unit 100 controls the operation of the substrate processing apparatus 1 by reading and executing programs stored in the storage medium 38 . The program may be stored in the computer-readable storage medium 38 and may be installed in the storage medium 38 of the control unit 100 from another storage medium.

The computer-readable storage medium 38 includes, for example, a hard disk (HD), flexible disk (FD), compact disk (CD), magnet optical disk (MO), memory card, and the like.

<Structure of Processing Tank for Etching>
Next, the processing bath 27 for etching will be described with reference to FIG. FIG. 2 is a schematic block diagram showing the configuration of the etching treatment tank 27 according to the embodiment.

In the processing tank 27 for etching, an etchant is used to remove the silicon nitride film (SiN) 8A (see FIG. 3A) and the silicon oxide film (SiO ₂ ) 8B (see FIG. 3A) formed on the substrate 8. The silicon nitride film 8A is selectively etched.

In the nitride film etching process, a solution prepared by adding a silicon (Si)-containing compound to a phosphoric acid (H ₃ PO ₄ ) aqueous solution to adjust the silicon concentration is generally used as an etchant.

Methods for adjusting the silicon concentration include a method of immersing a dummy substrate in an existing phosphoric acid aqueous solution to dissolve silicon (seasoning), and a method of dissolving a silicon-containing compound such as colloidal silica in a phosphoric acid aqueous solution. There is also a method of adjusting the silicon concentration by adding an aqueous solution of a silicon-containing compound to an aqueous solution of phosphoric acid.

The etching treatment tank 27 includes a phosphoric acid aqueous solution supply section 40, a phosphoric acid aqueous solution discharge section 41, a pure water supply section 42, a silicon supply section 43, an inner tank 44, an outer tank 45, and a temperature control tank. 46.

The phosphoric acid aqueous solution supply unit 40 has a phosphoric acid aqueous solution supply source 40A, a phosphoric acid aqueous solution supply line 40B, and a first flow regulator 40C.

The phosphoric acid aqueous solution supply source 40A is a tank that stores the phosphoric acid aqueous solution. The phosphoric acid aqueous solution supply line 40B connects the phosphoric acid aqueous solution supply source 40A and the temperature control tank 46, and supplies the phosphoric acid aqueous solution to the temperature control tank 46 from the phosphoric acid aqueous solution supply source 40A.

The first flow rate regulator 40C is provided in the phosphoric acid aqueous solution supply line 40B and adjusts the supply amount of the phosphoric acid aqueous solution supplied to the temperature control tank 46 . The first flow regulator 40C is composed of an on-off valve, a flow control valve, a flow meter, and the like.

The pure water supply unit 42 has a pure water supply source 42A, a pure water supply line 42B, and a second flow regulator 42C. The pure water supply unit 42 supplies pure water (DIW) to the outer tank 45 in order to replenish the moisture evaporated by heating the etchant.

The pure water supply line 42B connects the pure water supply source 42A and the outer tank 45, and supplies pure water of a predetermined temperature to the outer tank 45 from the pure water supply source 42A.

The second flow regulator 42C is provided in the pure water supply line 42B and adjusts the amount of pure water supplied to the outer tank 45 . The second flow regulator 42C is composed of an on-off valve, a flow control valve, a flow meter, and the like. The temperature, phosphoric acid concentration, and silicon concentration of the etchant are adjusted by adjusting the amount of pure water supplied by the second flow controller 42C. The second flow regulator 42C constitutes a temperature control section, a phosphoric acid concentration control section, and a silicon concentration control section.

The silicon supply unit 43 has a silicon supply source 43A, a silicon supply line 43B, and a third flow regulator 43C.

43 A of silicon|silicone supply sources are tanks which store silicon-containing compound aqueous solution. The silicon supply line 43B connects the silicon supply source 43A and the temperature control tank 46, and supplies the silicon-containing compound aqueous solution to the temperature control tank 46 from the silicon supply source 43A.

The third flow rate adjuster 43C is provided in the silicon supply line 43B and adjusts the supply amount of the silicon-containing compound aqueous solution supplied to the temperature control tank 46 . The third flow regulator 43C is composed of an on-off valve, a flow control valve, a flow meter, and the like.

The silicon-containing compound aqueous solution is supplied when the etching process is finished and a preliminary liquid to be supplied when the etching liquid is completely replaced is generated. In addition, the silicon supply unit 43 may be capable of supplying the silicon-containing compound aqueous solution to the outer tank 45 . In this case, the silicon supply unit 43 can supply the silicon-containing compound aqueous solution to the outer tank 45 when the concentration of silicon in the etchant decreases during the etching process.

The inner bath 44 is open at the top, and the etchant is supplied to the vicinity of the top. In the inner tank 44 , the lot (a plurality of substrates 8 ) is immersed in the etching liquid by the substrate lifting mechanism 29 , and the substrates 8 are etched. The inner bath 44 constitutes a substrate processing bath.

The outer tub 45 is provided around the upper portion of the inner tub 44 and has an open top. The etchant overflowing from the inner tank 44 flows into the outer tank 45 . A preliminary liquid is supplied from a temperature control tank 46 to the outer tank 45 . Pure water is supplied to the outer tank 45 from the pure water supply unit 42 .

The outer tank 45 is provided with a temperature sensor 80 for detecting the temperature of the etchant and a phosphoric acid concentration sensor 81 for detecting the phosphoric acid concentration of the etchant. Signals generated by the sensors 80 and 81 are input to the control section 100 (see FIG. 1).

The outer tub 45 and the inner tub 44 are connected by a first circulation line 50 . One end of the first circulation line 50 is connected to the outer bath 45 , and the other end of the first circulation line 50 is connected to the processing liquid supply nozzle 49 installed inside the inner bath 44 .

The first circulation line 50 is provided with a first pump 51 , a first heater 52 and a filter 53 in this order from the outer tank 45 side. The etchant in the outer tank 45 is heated by the first heater 52 and flows into the inner tank 44 from the processing liquid supply nozzle 49 .

The first heater 52 adjusts the temperature of the etchant supplied to the inner bath 44 . Also, the first circulation line 50 is provided with a silicon concentration sensor 82 for detecting the silicon concentration in the etchant. A signal generated by silicon concentration sensor 82 is input to control unit 100 . The first heater 52 constitutes a temperature control section.

By driving the first pump 51 , the etchant is sent from the outer bath 45 through the first circulation line 50 into the inner bath 44 . In addition, the etchant overflows from the inner tank 44 and flows out to the outer tank 45 again.

Thus, a circulation path 55 for the etchant is formed. That is, the circulation path 55 is formed by the outer tank 45 , the first circulation line 50 and the inner tank 44 . In the circulation path 55 , the outer tank 45 is provided upstream of the first heater 52 with respect to the inner tank 44 .

In the temperature control tank 46, the phosphoric acid aqueous solution supplied from the phosphoric acid aqueous solution supply unit 40 is stored as a preliminary liquid. In the temperature control tank 46, a preliminary liquid is generated and stored by mixing the phosphoric acid aqueous solution supplied from the phosphoric acid aqueous solution supply unit 40 and the silicon-containing compound aqueous solution supplied from the silicon supply unit 43.

For example, in the temperature control tank 46, when all the etchants in the inner tank 44 and the outer tank 45 are replaced, a preliminary liquid in which the phosphoric acid aqueous solution and the silicon-containing compound aqueous solution are mixed is generated and stored. Further, in the temperature control tank 46, when part of the etchant is replaced during the etching process, a phosphoric acid aqueous solution is stored as a preliminary liquid.

A second circulation line 60 for circulating the preliminary liquid in the temperature control tank 46 is connected to the temperature control tank 46 . One end of a supply line 70 is connected to the temperature control tank 46 . The other end of the supply line 70 is connected to the outer bath 45 .

A second pump 61 and a second heater 62 are provided in the second circulation line 60 . By driving the second pump 61 with the second heater 62 turned on, the preliminary liquid in the temperature control tank 46 is heated and circulated. The second heater 62 adjusts the temperature of the preliminary liquid. The second heater 62 constitutes a temperature control section.

The supply line 70 is provided with a third pump 71 and a fourth flow regulator 72 . The fourth flow rate regulator 72 adjusts the supply amount of the preliminary liquid supplied to the outer tank 45 . The fourth flow regulator 72 is composed of an on-off valve, a flow control valve, a flow meter, and the like. The temperature, phosphoric acid concentration, and silicon concentration of the etchant are adjusted by adjusting the supply amount of the preliminary liquid by the fourth flow rate regulator 72 . The fourth flow rate regulator 72 constitutes a temperature control section, a phosphoric acid concentration control section, and a silicon concentration control section.

The preliminary liquid stored in the temperature control tank 46 is supplied to the outer tank 45 via the supply line 70 when replacing all or part of the etching liquid.

The phosphoric acid aqueous solution discharge part 41 discharges the etchant when all or part of the etchant used in the etching process is replaced. The phosphoric acid aqueous solution discharge part 41 has a discharge line 41A, a fifth flow regulator 41B, and a cooling tank 41C.

The discharge line 41A is connected to the first circulation line 50 . The fifth flow rate adjuster 41B is provided in the discharge line 41A and adjusts the discharge amount of the discharged etchant. The fifth flow regulator 41B is composed of an on-off valve, a flow control valve, a flow meter, and the like.

The cooling tank 41C temporarily stores and cools the etchant flowing through the discharge line 41A. The discharge amount is adjusted by the fifth flow controller 41B, and for example, pure water is supplied to adjust the temperature, phosphoric acid concentration, and silicon concentration of the etchant. The fifth flow regulator 41B constitutes a temperature control section, a phosphoric acid concentration control section, and a silicon concentration control section.

The opening and closing of the on-off valves constituting the first flow regulator 40C to the fifth flow regulator 41B and the degree of opening of the flow control valves are controlled by actuators (not shown) based on signals from the control unit 100. is changed. That is, the control unit 100 controls the on-off valves and the flow rate control valves that constitute the first to fifth flow rate regulators 40C to 41B.

<Outline of etching process>
Next, an etching process according to the embodiment will be described with reference to FIGS. 3A to 3D. FIG. 3A is a schematic diagram showing a cross-section of the substrate 8 before etching. FIG. 3B is a schematic diagram showing the state of the substrate 8 after the etching process has progressed. FIG. 3C is a schematic diagram showing the state of the substrate 8 after the etching process has progressed further. FIG. 3D is a schematic diagram showing the state of the substrate 8 after the etching process is completed.

As shown in FIG. 3A, a plurality of silicon nitride films 8A and silicon oxide films 8B are alternately laminated on the substrate 8 before etching. Further, the substrate 8 is formed with a plurality of grooves 8C into which an etchant penetrates to etch the laminated silicon nitride film 8A.

When the substrate 8 is immersed in the inner bath 44 and the etching process is started, as shown in FIG. 3B, the silicon nitride film 8A near the groove 8C is first etched. That is, in the etching process, the silicon nitride film 8A is sequentially etched from the one closest to the groove 8C.

The components of the silicon nitride film 8A eluted into the etchant by the etching are discharged into the groove 8C through the gap 8D formed by the etching of the silicon nitride film 8A and out of the substrate 8 through the groove 8C. Etching progresses by replacing the etchant in the groove 8C and the gap 8D with new etchant.

Therefore, as the etching process progresses, the distance from the etched portion to the groove 8C increases as shown in FIG. 3C. That is, the distance by which the components of the silicon nitride film 8A dissolved in the etchant are discharged to the outside of the substrate 8 becomes longer.

Therefore, when the etching rate of the silicon nitride film 8A is high, the concentration of silicon contained in the etchant for the grooves 8C and the gaps 8D increases. In particular, the concentration of silicon in the etchant is high at the back side of the groove 8C, that is, at the gap 8D formed at a location with a long distance from the surface of the substrate 8 .

Therefore, silicon oxide may be deposited on silicon oxide film 8B while the etchant containing the components of silicon nitride film 8A that has been etched and eluted is discharged to the outside of substrate 8 . As the etching process progresses further, the gaps 8D on both sides communicate with each other, as shown in FIG. 3D.

<Details of etching process>
Next, details of the etching process according to the embodiment will be described with reference to FIGS. 4 to 7. FIG. FIG. 4 is a diagram showing the transition of the silicon concentration in the etchant and the temperature of the etchant in the etching process according to the embodiment.

As shown in FIG. 4, the etching process according to the embodiment includes a first etching process, a second etching process, and a third etching process.

The first etching process is performed at a first time interval from time t0 at which the etching process is started to a predetermined time t1. A second etching process is performed at a second time interval from time t1 to a predetermined time t2 following the first etching process. A third etching process is performed following the second etching process for a third time interval from time t2 to a predetermined time t3 when the etching process is completed.

In the first etching process, the silicon concentration in the etchant is a predetermined first concentration Ca, and the temperature of the etchant is a predetermined first temperature Ta. In the second etching process, the silicon concentration in the etchant is a second concentration Cb higher than the first concentration Ca, and the temperature of the etchant is a second temperature Tb higher than the first temperature Ta.

Furthermore, in the third etching process, the silicon concentration in the etching liquid is a predetermined third concentration Cc that is higher than the second concentration Cb, and the temperature of the etching liquid is a predetermined third temperature Tc that is higher than the second temperature Tb.

Details of the first concentration Ca to the third concentration Cc will now be described with reference to FIG. FIG. 5 is a diagram showing an example of the relationship between the silicon concentration in the etchant and the etching rate in etching the silicon oxide film 8B and the silicon oxide.

As shown in FIG. 5, even if the silicon oxide film 8B and the silicon oxide are made of the same SiO ₂ , the etching rates are different because the film quality is different. The etching rate of both the silicon oxide film 8B and the silicon oxide decreases as the silicon concentration in the etchant increases, and when the silicon concentration exceeds a predetermined threshold value, the silicon oxide film 8B is not dissolved by etching but instead is oxidized. matter precipitates.

As shown in FIG. 5, the first concentration Ca is a concentration that etches not only the silicon oxide but also the silicon oxide film 8B. The third concentration Cc is a concentration at which silicon oxide is etched while the silicon oxide film 8B is not etched (that is, the etching rate is substantially zero).

The second concentration Cb is a concentration between the first concentration Ca and the third concentration Cc. That is, the second concentration Cb is a concentration at which not only the silicon oxide but also the silicon oxide film 8B is etched, but the etching rate itself is lower than that of the first concentration Ca.

Here, the higher the silicon concentration in the etchant (for example, the second concentration Cb or the third concentration Cc), the higher the etching rate of the silicon nitride film 8A with respect to the silicon oxide film 8B (that is, the higher the selectivity). .

On the other hand, when the substrate 8 on which the silicon nitride film 8A and the silicon oxide film 8B are highly laminated is treated with an etchant having a high silicon concentration, silicon oxide is formed especially on the silicon oxide film 8B located below the trench 8C. Precipitation was a concern.

This is because the lower side of the groove 8C is less likely to be replaced with a new etchant than the upper side of the groove 8C, so the silicon concentration inevitably increases. Therefore, the inventors of the present application made a thorough study of the details of this phenomenon and obtained new findings.

FIG. 6 is a diagram showing transition of the film thickness of the silicon oxide film 8B when the silicon concentration in the etchant is the second concentration Cb. From these results, when the etching process is performed with the second concentration Cb having a relatively high silicon concentration, silicon oxide is certainly deposited on the silicon oxide film 8B in the initial stage, and the phenomenon that the film thickness of the silicon oxide film 8B increases. be seen.

On the other hand, it was found that after the initial stage of the etching process, even at the second concentration Cb, which is a relatively high silicon concentration, the increase in the film thickness of the silicon oxide film 8B stops. That is, it was found that the phenomenon in which silicon oxide is deposited on the silicon oxide film 8B stops after the initial stage of the etching process.

It is considered that this result is caused by the following phenomena occurring in the substrate 8 . At the initial stage of the etching process, since the amount of etching of the silicon nitride film 8A relative to the volume of the trench 8C is large, the silicon concentration inside the trench 8C (particularly below the trench 8C) tends to be high. Therefore, in the initial stage of the etching process, a phenomenon occurs in which silicon oxide is deposited on the silicon oxide film 8B.

On the other hand, after the initial stage of the etching process, the volume of the groove 8C increases due to the formation of the gap 8D, while the etching amount of the silicon nitride film 8A does not change much from the initial stage. The internal silicon concentration is relatively lowered. Therefore, it is considered that the phenomenon in which silicon oxide deposits on the silicon oxide film 8B ceases after the initial stage of the etching process.

Based on the results of FIG. 6, in the embodiment, as shown in FIG. 4, the first etching process, which is the initial stage of the etching process, is performed at a first concentration Ca having a relatively low silicon concentration. This can suppress the phenomenon that silicon oxide is deposited on the silicon oxide film 8B in the initial stage of the etching process.

In the second etching process, which is performed after the initial stage of the etching process has passed and the phenomenon in which silicon oxide deposits on the silicon oxide film 8B has subsided, the silicon concentration is performed at a relatively high second concentration Cb. . As a result, the selection ratio of the silicon nitride film 8A to the silicon oxide film 8B can be increased, so that the etching process can be performed more efficiently.

In the embodiment, even if the second etching process is performed with the second concentration Cb having a relatively high silicon concentration, as shown in FIG. there is Therefore, according to the embodiment, it is possible to suppress the phenomenon that the space between adjacent silicon oxide films 8B is clogged with silicon oxide.

Furthermore, in the embodiment, after the gaps 8D on both sides are communicated by the second etching process and the silicon nitride film 8A is removed from the substrate 8, the third etching process is performed. Here, by performing the third etching process with a third concentration Cc having a higher silicon concentration, only the silicon oxide deposited on the silicon oxide film 8B can be etched, as shown in FIG.

That is, in the embodiment, by performing the third etching process after the silicon nitride film 8A is removed from the substrate 8, the silicon oxide deposited on the silicon oxide film 8B can be removed. Therefore, according to the embodiment, it is possible to form the gaps 8D at desired intervals in the substrate 8 .

In the embodiment, an example of using the phosphating solution having the silicon concentration of the third concentration Cc as the treatment for removing the silicon oxide deposited on the silicon oxide film 8B is shown, but the silicon oxide is removed. Processing is not limited to this example. For example, SC-1 may be used as an etchant to remove silicon oxide deposited on the silicon oxide film 8B.

Further, as shown in FIG. 4, in the first to third etching processes, the temperature of the etchant should be increased as the silicon concentration in the etchant is increased. By increasing the temperature of the etchant in this manner, the saturation concentration of silicon in the etchant can be increased, so that the silicon concentration in the etchant can be set to the desired second concentration Cb or third concentration Cc. can.

FIG. 7 is a diagram for explaining etching processing in the substrate processing apparatus 1 according to the embodiment. As shown in FIG. 7A, in the embodiment, the substrate processing apparatus 1 is provided with three processing baths 27A, 27B, and 27C.

The processing bath 27A stores a phosphating solution having a silicon concentration of a first concentration Ca, the processing bath 27B stores a phosphating solution having a silicon concentration of a second concentration Cb, and the processing bath 27C stores a phosphating solution having a silicon concentration of a second concentration Cb. A phosphating solution having a silicon concentration of the third concentration Cc is stored.

Then, as shown in (a) of FIG. 7, the control unit 100 transports the substrate 8 to the processing tank 27A, and performs the first etching process on the substrate 8 in the processing tank 27A. Next, as shown in FIG. 7B, the control unit 100 transfers the substrate 8 from the processing tank 27A to the processing tank 27B, and performs the second etching process on the substrate 8 in the processing tank 27B.

Finally, as shown in (c) of FIG. 7, the control unit 100 transfers the substrate 8 from the processing bath 27B to the processing bath 27C, and performs the third etching process on the substrate 8 in the processing bath 27C. As a result, the substrate 8 can be smoothly subjected to the first to third etching processes according to the embodiment.

In the embodiment, three processing baths 27A to 27C having different silicon concentrations are prepared, and the substrate 8 is subjected to the first etching processing to the third etching processing. The process of performing the third etching process is not limited to this example.

For example, in one processing bath 27, the silicon concentration is first set to the first concentration Ca, then changed to the second concentration Cb at time t1, and further changed to the third concentration Cc at time t2. You can change it.

<Modification>
Next, various modifications of the embodiment will be described with reference to FIGS. 8 to 14. FIG. FIG. 8 is a diagram showing transitions of the silicon concentration in the etchant and the temperature of the etchant in the etching process according to Modification 1 of the embodiment. As shown in FIG. 8, the substrate 8 may be etched only by the first etching process and the second etching process, and the third etching process may be omitted.

FIG. 9 is a diagram showing transitions of the silicon concentration in the etchant and the temperature of the etchant in the etching process according to Modification 2 of the embodiment. As shown in FIG. 9, the etching process to be applied to the substrate 8 continues the first etching process even after the time t1 has elapsed, and the second etching process is not performed thereafter, and the etching process is performed at a predetermined time t2a after the first etching process. You may transfer to a 3rd etching process.

FIG. 10 is a diagram showing the transition of the silicon concentration in the etchant and the temperature of the etchant in the etching process according to Modification 3 of the embodiment. As shown in FIG. 10, the etching process applied to the substrate 8 directly shifts from the first etching process to the third etching process after the time t1 has passed, and the substrate 8 is directly subjected to the third etching process to complete the etching process. You may

FIG. 11 is a diagram showing transitions of the silicon concentration in the etchant and the temperature of the etchant in the etching process according to Modification 4 of the embodiment. As shown in FIG. 11, the etching process applied to the substrate 8 directly shifts from the first etching process to the third etching process after the elapse of time t1, and then shifts from the third etching process to the second etching process. good too.

FIG. 12 is a diagram for explaining etching processing in the substrate processing apparatus 1 according to Modification 5 of the embodiment. As shown in FIG. 12(a), in the fifth modification, the substrate processing apparatus 1 is provided with more processing baths 27B than processing baths 27A. For example, in modification 5, the substrate processing apparatus 1 is provided with one processing bath 27A, three processing baths 27B1 to 27B3, and one processing bath 27C.

The processing bath 27A stores a phosphating solution having a silicon concentration of a first concentration Ca, the processing baths 27B1 to 27B3 store a phosphating solution having a silicon concentration of a second concentration Cb, and the processing bath 27C. A phosphating solution having a silicon concentration of the third concentration Cc is stored in .

Then, as shown in FIG. 12A, the control unit 100 transports the substrate 8-1 to the processing tank 27A, and performs the first etching process on the substrate 8-1 in the processing tank 27A.

Next, as shown in FIG. 12B, the control unit 100 transfers the substrate 8-1 from the processing tank 27A to the processing tank 27B1, and performs the second etching process on the substrate 8-1 in the processing tank 27B1. Apply. At this time, the control unit 100 transports the substrate 8-2 of another lot to the empty processing bath 27A, and performs the first etching process on the substrate 8-2 in the processing bath 27A.

Here, as shown in FIG. 4, the second etching process requires a longer time than the first etching process (for example, about three to four times as long as the first etching process). Therefore, when the first etching process for the substrate 8-2 introduced later is completed, the second etching process for the substrate 8-1 introduced earlier is not yet completed.

Therefore, in Modified Example 5, as shown in FIG. 12C, the substrate 8-2 that has undergone the first etching treatment is transported to another treatment bath 27B2 and subjected to the second etching treatment. As a result, the second etching process can be applied to the substrate 8-2 that is input later without waiting until the second etching process for the substrate 8-1 that is input first is completed.

Further, when the substrate 8-2 is transported to another processing bath 27B2, the substrate 8-3 of another lot is transported to the empty processing bath 27A, and the substrate 8-3 is subjected to the first etching process in the processing bath 27A. .

Next, as shown in (d) of FIG. 12, the control section 100 transfers the substrate 8-3 from the processing tank 27A to the processing tank 27B3, and performs the second etching process on the substrate 8-3 in the processing tank 27B3. Apply. At that time, the control unit 100 transports the substrate 8-4 of another lot to the empty processing bath 27A, and performs the first etching process on the substrate 8-4 in the processing bath 27A.

Next, as shown in (e) of FIG. 12, the control unit 100 transfers the substrate 8-1 that has undergone the second etching process from the processing bath 27B1 to the processing bath 27C, and the substrate 8-1 is transferred to the processing bath 27C. 1 is subjected to a third etching process.

At this time, the control unit 100 transfers the substrate 8-4 that has undergone the first etching process from the processing tank 27A to the empty processing tank 27B1, and performs the second etching process on the substrate 8-4 in the processing tank 27B1. Further, the control unit 100 transports the substrate 8-5 of another lot to the empty processing tank 27A, and performs the first etching process on the substrate 8-5 in the processing tank 27A.

Here, as shown in FIG. 4, the third etching process is completed in about the same time as the first etching process. Therefore, the third etching process for the previously input substrate 8-1 is completed at approximately the same timing as the completion of the second etching process for the substrate 8-2 that is subsequently input.

Therefore, as shown in (f) of FIG. 12, the control unit 100 removes the substrate 8-2 from the processing bath 27B2 when the substrate 8-1 that has been subjected to the third etching process is unloaded from the processing bath 27C. The substrate 8-2 is transferred to the processing tank 27C, and the substrate 8-2 is subjected to the third etching process in the processing tank 27C.

At this time, the control unit 100 transfers the substrate 8-5 that has undergone the first etching process from the processing tank 27A to the empty processing tank 27B2, and performs the second etching process on the substrate 8-5 in the processing tank 27B2. Further, the control unit 100 transports the substrate 8-6 of another lot to the empty processing tank 27A, and performs the first etching process on the substrate 8-6 in the processing tank 27A.

As described above, in Modified Example 5, the number of processing tanks 27B for performing the second etching process, which takes the longest processing time, is reduced to the number of processing tanks 27A for performing the first etching process and the number of processing tanks 27A for performing the third etching process. Prepare more than the processing tank 27C. As a result, the substrate 8 can be smoothly subjected to the first to third etching processes without having the substrate 8 wait for processing inside the substrate processing apparatus 1 .

FIG. 13 is a diagram for explaining etching processing in the substrate processing apparatus 1 according to Modification 6 of the embodiment. As shown in FIG. 13(a), in the sixth modification, the substrate processing apparatus 1 is provided with two processing baths 27D and 27E.

A phosphating solution having a first silicon concentration Ca is stored in the processing bath 27D, and a phosphating solution having a third silicon concentration Cc is stored in the processing bath 27E.

Then, as shown in (a) of FIG. 13, the control unit 100 transports the substrate 8-7 to the processing tank 27D, and performs the first etching process and the second etching process on the substrate 8-7 in the processing tank 27D. . Specifically, in the processing tank 27D, supply/discharge control is performed to control the concentration of silicon in the etchant to the first concentration Ca until time t1.

After the time t1, the control unit 100 does not perform the supply/discharge control, thereby gradually increasing the concentration of silicon in the etchant to the second concentration Cb. Thereby, it is possible to shift from the first etching process to the second etching process in the processing tank 27D.

Next, as shown in (b) of FIG. 13, the control unit 100 transfers the substrate 8-7 from the processing tank 27D to the processing tank 27E, and performs the third etching process on the substrate 8-7 in the processing tank 27E. . This completes the etching process for the substrates 8-7 of one lot.

Since the silicon nitride film 8A has already been removed from the substrate 8-7 in the third etching process, the silicon concentration in the processing tank 27E does not change from the third concentration Cc.

Next, as shown in (c) of FIG. 13, the controller 100 replaces the etchant in the processing bath 27D, and as shown in (d) of FIG. A phosphating solution having a concentration of Ca is stored.

Then, as shown in (e) of FIG. 13, the control unit 100 transports the substrate 8-8 of the next lot to the processing tank 27D, and the substrate 8-8 is subjected to the first etching process and the second etching process in the processing tank 27D. Etching is applied. The first etching process and the second etching process are the same as the process shown in FIG. 13(a).

Then, as shown in (b) of FIG. 13, the controller 100 transfers the substrate 8-8 of the next lot from the processing bath 27D to the processing bath 27E, and transfers the substrate 8-8 to the substrate 8-8 in the processing bath 27E. Etching is applied. This completes the etching process for the substrate 8-8 of the next lot.

In this manner, the first etching process and the second etching process are performed in one of the processing tanks 27D, and the third etching process is performed in the other processing tank 27E, whereby the first etching process is performed in the two processing tanks 27D and 27E. - A third etching process may be applied to the substrate 8 .

FIG. 14 is a diagram for explaining etching processing in the substrate processing apparatus 1 according to Modification 7 of the embodiment. As shown in FIG. 14(a), in the seventh modification, the substrate processing apparatus 1 is provided with two processing tanks 27F and 27G.

A phosphating solution having a silicon concentration of a first concentration Ca is stored in the processing bath 27F, and a phosphating solution having a silicon concentration of a second concentration Cb is stored in the processing bath 27G.

Then, as shown in FIG. 14A, the control unit 100 transports the substrate 8-9 to the processing tank 27F, and performs the first etching process on the substrate 8-9 in the processing tank 27F. Specifically, in the processing tank 27F, supply/discharge control is performed to control the concentration of silicon in the etchant to the first concentration Ca until time t1.

Then, as shown in FIG. 14B, the control unit 100 stops the supply/discharge control after time t1, increases the silicon concentration in the etchant to the second concentration Cb, and then removes the substrate 8-. 9 is transferred from the processing bath 27F to the processing bath 27G.

Then, the control section 100 performs the second etching process and the third etching process on the substrate 8-9 in the processing bath 27G. Specifically, in the processing bath 27G, the supply/discharge control is performed to control the concentration of silicon in the etchant to the second concentration Cb until time t2.

After time t2, the control unit 100 does not perform such supply/discharge control, so the concentration of silicon in the etchant gradually increases to the third concentration Cc. Thereby, it is possible to shift from the second etching process to the third etching process in the processing bath 27G. Then, the etching process for the substrates 8-9 of one lot is completed.

Next, as shown in (c) of FIG. 14, the controller 100 replaces the etchant in the processing bath 27G, and as shown in (d) of FIG. A phosphating solution having a concentration of Ca is stored.

Then, as shown in (e) of FIG. 14, the control unit 100 transports the substrate 8-10 of the next lot to the processing tank 27G, and performs the first etching process on the substrate 8-10 in the processing tank 27G. Specifically, in the processing tank 27G, the supply/discharge control is performed to control the concentration of silicon in the etchant to the first concentration Ca until time t1.

Then, as shown in (f) of FIG. 14, the control unit 100 stops the supply/discharge control after time t1, increases the silicon concentration in the etching solution to the second concentration Cb, and then performs the next lot. The substrate 8-10 is transported from the processing bath 27G to the processing bath 27F.

Then, the control unit 100 performs the second etching process and the third etching process on the substrates 8-10 of the next lot in the processing tank 27F. Specifically, in the processing bath 27F, supply/discharge control is performed to control the concentration of silicon in the etchant to the second concentration Cb until time t2.

After time t2, the control unit 100 does not perform the supply/discharge control, thereby gradually increasing the concentration of silicon in the etchant to the third concentration Cc. Thereby, it is possible to shift from the second etching process to the third etching process in the processing bath 27F. Then, the etching process for the substrates 8-10 of the next lot is completed.

Next, although not shown, the control unit 100 replaces the etchant in the processing tank 27F, and the phosphating liquid having the silicon concentration of the first concentration Ca is stored in the processing tank 27G. It returns to the state shown in (a).

Thus, by alternately performing the first etching process, the second etching process and the third etching process in the two processing tanks 27F and 27G, the first etching process to the third etching process are performed in the two processing tanks 27F and 27G. A treatment can be applied to the substrate 8 .

The substrate processing apparatus 1 according to the embodiment includes a substrate processing bath (processing bath 27A) in which etching processing is performed by immersing a substrate 8 having a silicon oxide film and a silicon nitride film formed thereon in a phosphating solution, and a substrate processing bath. and a control unit 100 for controlling (processing bath 27A). Then, the control unit 100 controls the silicon concentration in the phosphating solution to be equal to that of the silicon oxide film during the first time interval from when the substrate 8 starts to be immersed in the substrate processing tank (processing tank 27A). Control is made to the first silicon concentration (first concentration Ca) at which 8B is etched. As a result, the silicon nitride film 8A can be accurately etched even on the substrate 8 on which the silicon nitride film 8A and the silicon oxide film 8B are highly laminated.

Further, the substrate processing apparatus 1 according to the embodiment includes another substrate processing bath (processing bath 27B) for performing etching processing, and a substrate processing bath (processing bath 27A) and another substrate processing bath (processing bath 27B). and a transport unit (lot transport mechanism 19) that transports the substrate 8 by means of the . Further, the control unit 100 sets the silicon concentration in the phosphating solution stored in another substrate processing bath (processing bath 27B) to a second silicon concentration (second concentration Ca) higher than the first silicon concentration (first concentration Ca). Control to 2 concentrations Cb). Then, the control unit 100 transports the substrate 8 immersed in the substrate processing bath (processing bath 27A) until the first time interval elapses to another substrate processing bath (processing bath 27B) and immerses it. As a result, the substrate 8 can be smoothly subjected to the first to third etching processes according to the embodiment.

Further, in the substrate processing apparatus 1 according to the embodiment, the other substrate processing baths (processing baths 27B) are provided in a larger number than the substrate processing baths (processing baths 27A). As a result, the substrate 8 can be smoothly subjected to the first to third etching processes without having the substrate 8 wait for processing inside the substrate processing apparatus 1 .

<Details of etching process>
Next, details of the etching process performed by the substrate processing apparatus 1 according to the embodiment will be described with reference to FIG. 15 . FIG. 15 is a flow chart showing the procedure of the etching process according to the embodiment.

First, the control unit 100 performs a first etching process on the substrate 8 at a first time interval from time t0 when the etching process is started to a predetermined time t1 (step S101). In such a first etching process, the controller 100 controls the silicon concentration in the etchant to a predetermined first concentration Ca and the temperature of the etchant to a predetermined first temperature Ta.

Next, the controller 100 performs a second etching process on the substrate 8 at a second time interval from time t1 to a predetermined time t2 (step S102). In such a second etching process, the controller 100 controls the silicon concentration in the etchant to a predetermined second concentration Cb and the temperature of the etchant to a predetermined second temperature Tb.

Finally, the control unit 100 performs a third etching process on the substrate 8 at a third time interval from time t2 to a predetermined time t3 (step S103) to complete the process. In the third etching process, the controller 100 controls the concentration of silicon in the etchant to a predetermined third concentration Cc and the temperature of the etchant to a predetermined third temperature Tc.

The substrate processing method according to the embodiment includes an etching step of etching the substrate 8 having the silicon oxide film 8B and the silicon nitride film 8A formed thereon with a phosphating solution. In the etching process, the concentration of silicon in the phosphating solution is reduced to the first level at which the silicon oxide film 8B is etched from the start point (time t0) until the first time interval elapses (up to time t1). The silicon concentration (first concentration Ca) is set. As a result, the silicon nitride film 8A can be accurately etched even on the substrate 8 on which the silicon nitride film 8A and the silicon oxide film 8B are highly laminated.

Further, in the substrate processing method according to the embodiment, the silicon concentration in the phosphating solution is changed to the first silicon concentration (first concentration Ca) after the first time interval (time t1). A higher second silicon concentration (second concentration Cb) is set. As a result, the selection ratio of the silicon nitride film 8A to the silicon oxide film 8B can be increased, so that the etching process can be performed more efficiently.

In addition, in the substrate processing method according to the embodiment, in the etching step, the concentration of silicon in the phosphating solution is reduced to A third silicon concentration (third concentration Cc) higher than the silicon concentration (second temperature Tb) of No. 2 is set. Thereby, the silicon oxide deposited on the silicon oxide film 8B can be removed.

Further, in the substrate processing method according to the embodiment, the third silicon concentration (third concentration Cc) is a concentration at which the silicon oxide film 8B is not etched. Thereby, only the silicon oxide deposited on the silicon oxide film 8B can be etched.

Further, in the substrate processing method according to the embodiment, the etching process is performed by increasing the temperature of the phosphating solution from the time when the first time interval elapses (time t1) until the first time interval elapses (until time t1). ) to a second temperature (second temperature Tb) higher than the first temperature (first temperature Ta). As a result, the saturation concentration of silicon in the etchant can be increased, so that the concentration of silicon in the etchant can be the desired second concentration Cb.

Further, in the substrate processing method according to the embodiment, the temperature of the phosphating solution is changed to the second temperature after the first time interval and the second time interval (time t2). A third temperature (third temperature Tc) higher than the temperature (second temperature Tb) is set. As a result, the saturation concentration of silicon in the etchant can be increased, so that the concentration of silicon in the etchant can be set to the desired third concentration Cc.

Although the embodiments of the present disclosure have been described above, the present disclosure is not limited to the above-described embodiments, and various modifications can be made without departing from the scope of the present disclosure. For example, in the above embodiment, an example was shown in which a solution obtained by adding a silicon-containing compound to an aqueous solution of phosphoric _acid to adjust the silicon concentration was used as an etching solution. You may

It should be considered that the embodiments disclosed this time are illustrative in all respects and not restrictive. Indeed, the above-described embodiments may be embodied in many different forms. Also, the above-described embodiments may be omitted, substituted, or modified in various ways without departing from the scope and spirit of the appended claims.

1 substrate processing apparatus 8, 8-1 to 8-10 substrate 8A silicon nitride film 8B silicon oxide film 27, 27A to 27G processing tank 100 control unit

Claims (8)

An etching step of etching the substrate on which the silicon oxide film and the silicon nitride film are formed with a phosphating solution,
The etching step includes
setting the silicon concentration in the phosphating solution to a first silicon concentration at which the silicon oxide film is etched during the first time interval from the start time until the elapse of the first time interval ;
bringing the temperature of the phosphating solution to a second temperature higher than the first temperature until the first time interval elapses from the time the first time interval elapses;
After the end of the first time interval, the temperature of the phosphating solution is set to a third temperature higher than the second temperature after a second time interval has passed.
Substrate processing method. The etching step includes
2. The substrate processing method according to claim 1, wherein the silicon concentration in the phosphating solution is set to a second silicon concentration higher than the first silicon concentration after the first time interval has passed. The etching step includes
3. After the first time interval has ended, the silicon concentration in the phosphating solution is set to a third silicon concentration higher than the second silicon concentration after the second time interval has elapsed. 2. The substrate processing method according to 2. 4. The substrate processing method according to claim 3, wherein the third silicon concentration is a concentration at which the silicon oxide film is not etched. a substrate processing bath for performing an etching process by immersing a substrate on which a silicon oxide film and a silicon nitride film are formed in a phosphating solution;
a control unit for controlling the substrate processing bath;
with
The control unit
The silicon concentration in the phosphating solution is set to a first silicon concentration at which the silicon oxide film is etched for a first time interval from when the substrate starts to be immersed in the substrate processing tank. control to
controlling the temperature of the phosphating solution from the time the first time interval elapses to a second temperature that is higher than the first temperature until the first time interval elapses;
After the end of the first time interval, the temperature of the phosphating solution is controlled to a third temperature higher than the second temperature after a second time interval has elapsed.
Substrate processing equipment. another substrate processing bath for performing the etching process;
further comprising a transport unit for transporting the substrate between the substrate processing bath and the other substrate processing bath;
The control unit
controlling the silicon concentration in the phosphating solution stored in the separate substrate processing tank to a second silicon concentration higher than the first silicon concentration;
6. The substrate processing apparatus according to claim 5 , wherein the substrate immersed in the substrate processing bath until the first time interval elapses is transported to the other substrate processing bath and immersed therein. The substrate processing apparatus according to claim 6 , wherein the number of the separate substrate processing baths is greater than that of the substrate processing baths. A storage medium storing a program for causing a computer to execute the substrate processing method according to any one of claims 1 to 4 .

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